Process of making hard cemented carbide materials



Patented Apr. 23,

UNITED STATES PATENT OFFICE PROCESS OF MAKING HARD CEMEN'IED CARBIDE MATERIALS Gregory J. Oomstock, Edgewood, Pa; asignor to Firth-Sterling Steel Company, lllc Pa., a corporation of Pennsylvania arport.

No Drawing. Application November as, 1932;

Serial No. ,49o v I mixture of hard metal carbide and metallic bindform a hard cemented carbide material such as can be used in tools, wire drawing dies, and the.

like.

At the present time it is known to make hard cemented carbide materials by grinding a mixture of powdered carbide such as tungsten carhide and powdered binding metal such as cobalt in a rolling barrel and thereafter sintering the mixed powder to produce the cemented material. In the grinding of the mixed powder in the rolling barrel, the powder becomes contaminated with'some iron or iron oxidewhlch abraded off from the surface of the barrel, so position of the powder after grin g is not exactly the same as that introducedyinto the'rolling barrel Furthermore, .the practice as now carried out can only be applied where the bind ble not only to those binding. agents which can readily be produced in powdered form by reduction of the oxides of the binding .agents .or by other common methods of producing metallic powders, but is also applicable to a variety of other metallic binding agents. The character of the hard cemented carbide material is influenced greatly by the composition of the binding agent. The binding agent not only acts to bond the particles of hard carbide, butalso imparts its own characteristics to" the final composition. Thus, in. many cases it is desirable to use as a binding agent some other metal or alloy than the commonly employed binding agents such as cobalt, nickel or iron. The difliculty in using other binding agentswhich would impart desirable properties to thefinal composition is in many cases that it is extrem make them into powder by reduc' is commonly done in the case of cobalt, nickel andiron.

difficult to i l iat'the com-.

the oxide, as 2 In accordance with my invention, the binding 9 agent which is used to bond the hard metal carbide in the cemented composition is mixed with the hard metal carbide by grinding the hard metal carbide 'in a container having its grinding 5 surface composed of the metallic binding agent; During the grinding, the hard metal carbide abrades off particles of the binding agent from the grinding surface of the container. The binding agent so abraded off is in extremely finely divided condition since it is obtained by the 1 abrasiveaction of the hard metal carbide on the grinding surface. The hard metal carbide is itself in a very finely divided condition when introduced into the container andthe particles of binding agent abraded off from the grinding surface of the container are necessarily smaller than the. particles of hard metal carbide. The. binding agent is used in relatively small proportions, as compared with the hard metal carbide, and for this reason it is a great advantage to have the particles of binding agent, as small as possible in order that they will be distributed to the. greatest extent throughout the powdered carbide. The mixture of hard metal carbide and metallic binding agent produced by the abrasive .action of the carbide on'the grinding surface of the mill composed of the binding agent is then sintered or'cemented in the usual way to produce the hard cemented carbide composition. The mixed powders may be first compacted and then sintered, or pressure and heat may be applied simultaneously to the mixed powders in order to produce the cemented composition.

If it is desired to produce a' hard cemented carbide material containing tungsten carbide and cobalt, the tungsten carbide prepared in any desired manner is introduced in powdered form into a rolling barrel which has its grinding surface composed of cobalt. This surfacemay be made by electroplating cobalt onto the interior surface of an ordinary cast iron rolling barrel or it may be made by melting and casting the cobalt. into a cylindrical lining which is thereafter inserted into the rolling barrel. The rolling barrel is charged with steel or iron balls, and. as the grinding progresses, the tungsten carbide abrades off particles of the cobalt from the grinding surface, producing a powdered mixture of .tungsten carbide and cobalt, both of which are in very finely divided condition, but especially the cobalt since. it has been abraded 'oil. from the cobalt surface. of the rolling barrel by the tlmgsten carbide which was in finely divided form previous to its introduction into the rolling barrel. This powdered mixture of tungsten carbide and cobalt is substantially free from extraneous matter such as iron or iron oxide which would be introduced had the tungsten carbide and cobalt both in powdered form been introduced and ground in a steel or iron rolling barrel.

A wide variety of metallic binding agents may be mixed in this manner with the hard metal carbide to produce mixed powders suitable for sintering to form the cem ted composition. The other usual binding agen such as nickel or iron may be mixed with the hard metal carbide by providing the rolling barrel or other container with a' grinding surface composed of either nickel or iron, If it is desired to use as the binding agent analloy of thwe metals or an alloy of other metals, a container having its grinding surface composed of such alloy'is used for grindin'gthe hard metal carbide. A binding agent may be introduced into a mixture of hard carbides by grinding a mixture of the hard carbides in a container having its grinding surface com posed of the binding agent.

The invention is particularly applicable to those metallic binding agents or alloys which it is diiiicult to produce in powdered form by reduction of their oxides or by other common methods of producing metallic powders.- These binding agents may be produced in powdered form mixed with the hard metal carbide by grinding the carbide in a container having its grinding surface composed of the binding agent-so as to abrade ofi particles of the binding agent. For example, manganese steel is very :tough and has a high resistance to abrasion and is, therefore, well adapted for use as a binding agent in hard carbide matefials. The disadvantage of manganese steel, however, is that it is extremely dimcult to produce in powdered form. In my process, manganese steel can be used as the binding agent by makingthe grinding surface ofthe rolling barrel of manganese steel and abrading oif particlesof the steel by grinding a hard metal carbide in the barrel. The invention is not restricted to any particular metal or alloy as the material of which the grinding surface is comthe grinding surface of the rolling barrel.

posed. Alloy steels other than manganese steel may be used in a similar. manner. 'Thus, the alloy steels referred to in my Patents No.

1,815,613, granted July 21, 1931, and No. 1,826,455,

V alloys of cobalt or nickel with titanium, or alloys of zirconium or chromium in the same manner.

If the grinding of the hardcarbide in contact with a surface composed of the binding agent is carried out for a long enough period, -all of therequired bindingagent may be produced by abrading on particles of the binding agent. On the other hand, if it is desired to modify the properties of the cemented composition by in-..

. eluding not only the usual metallic binding agents such as cobalt, nickel and iron, but also a binding agent which it is diflicult to produce in pow-- dered form, a hard carbide may be ground in contact with a cobalt surface in order to abrade ofi particles of cobalt and then in contact with a surface composed of manganesesteel in order to abrade off particles of the steel. If. it is desired to introduce manganese steel into a mixture of powdered tungsten carbide and cobalt, the powdered mixture may be ground in contact with a grindingsurface composed of manganese steel. In other words, the present invention may be used to provide in powdered form all of the binding agent desired in the composition or it may be used as a binding agent additive so as to incorporate additional binding'agents with other binding agents which have been formed in some other manner. As an example of the useof the present invention for incorporating a binding agent additive, tungsten carbide may be ground in contact with a grinding surface composed of a titanium alloy in order to abrade 01? particles of the alloy. Cobalt in powdered form may then be added to the mixture of tungsten carbide and titanium alloy and the grinding continued to produce a uniformmixture. In this case the titanium alloy is used in a relatively small procarbide, thorium carbide, uranium carbide, and

columbium carbide.

The term a relatively continuous surface composed of said binding agent has been used to distinguish the present process in which the hard carbide is ground in a container having its grinding surface composed of the binding agent from the prior known processes-in which mixing with the hard metal carbide.

I have given certain examples to illustrate the manner in which my process may be carried out. It is to be understood, however, that the invention may be otherwise practiced within the scope of the following claims.

I claim:

1. In the manufacture of hard cemented carbide material containing a hard metal carbide and a metallic binding agent, the step comprising grinding the hard metal carbide in a con tainer having a grinding surface containing. a

substantial amount of a metal of the group consisting of cobalt and nickel.

2. In the manufacture of hard cemented carbide material containing a hard metal carbide and a metallic binding agent, the step comprising grinding the hard metal carbide in a container having its surface composed of a material containing a substantial amountof ametalof the group consisting of cobalt and ,nickel.

3. The process of making hard metal compositions from powdered material, which comprises grinding a mixture of a hard metal carbide and a binding metal in a container composed of a chromium bearing alloy, whereby chromium is introduced into the mixture by the abrasive action of the mixture, and the mixture.

'4. Theprocess of making hard metal compositions from powdered material, which comthe binding agent is in powdered form before prises grinding-a mixture of a hard metal carbide and a binding metal of thegroup consistaction of the mixture, and sintering the mixture.

ing 01' cobalt and nickel in a container composed of a chromium bearing alloy, whereby chromium is introduced into the mixture by the abrasive 5. The process of making hard metal compositions from powdered material, which comprises grinding a mixture of a hard metal carbide and a binding metal of the group consisting oi cobalt and nickel in a container composed of an alloy of chromium and cobalt; whereby chromium is introduced into the mixture by the abrasive actionv of the mixture. and sintering the mixture.

6. The process of making hard metal compositions from powdered material, which comprises grinding a mixture of a hard metal carbide and a binding metal of the group consisting of cobalt and nickel in a chromium plated container, whereby chromium is introduced into the by the abrasive action of the mixa ture, and sintering the mixture.

" GREGORY J. COMSTOCK. 

